Distributed Database Management Systems - Database Management and Design - Lecture Slides, Slides of Introduction to Database Management Systems

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Distributed Database

Management Systems

In this chapter, you will learn:

• What a distributed database management system (DDBMS) is and what its components are
• How database implementation is affected by different levels of data and process distribution
• How transactions are managed in a distributed database environment
• How database design is affected by the distributed database environment

The Evolution of Distributed Database

Management Systems (continued)

• Centralized database required that corporate data be stored in a single central site
• Dynamic business environment and centralized database’s shortcomings spawned a demand for applications based on data access from different sources at multiple locations

Centralized Database

Management System

DDBMS Disadvantages

• Complexity of management and control
• Security
• Lack of standards
• Increased storage requirements
• Greater difficulty in managing the data environment
• Increased training cost

Distributed Processing

Environment

Characteristics of Distributed

Management Systems

• Application interface
• Validation
• Transformation
• Query optimization
• Mapping
• I/O interface
• Formatting
• Security
• Backup and recovery
• DB administration
• Concurrency control
• Transaction management

Characteristics of Distributed

Management Systems (continued)

• Must perform all the functions of a centralized DBMS
• Must handle all necessary functions imposed by the distribution of data and processing
• Must perform these additional functions transparently to the end user

DDBMS Components

• Must include (at least) the following components: - Computer workstations - Network hardware and software - Communications media - Transaction processor (or, application processor, or transaction manager) - Software component found in each computer that requests data - Data processor or data manager - Software component residing on each computer that stores and retrieves data located at the site - May be a centralized DBMS Docsity.com

Distributed Database

System Components

Single-Site Processing, Single-Site

Data (SPSD)

• All processing is done on single CPU or host computer (mainframe, midrange, or PC)
• All data are stored on host computer’s local disk
• Processing cannot be done on end user’s side of the system
• Typical of most mainframe and midrange computer DBMSs
• DBMS is located on the host computer, which is accessed by dumb terminals connected to it
• Also typical of the first generation of single-user microcomputer databases

Single-Site Processing,

Single-Site Data

(Centralized)

Multiple-Site Processing,

Single-Site Data

Multiple-Site Processing,

Multiple-Site Data (MPMD)

• Fully distributed database management system with support for multiple data processors and transaction processors at multiple sites
• Classified as either homogeneous or heterogeneous
• Homogeneous DDBMSs
  • Integrate only one type of centralized DBMS over a network Docsity.com